MySQL 5.7 Release Notes
The performance of an NDB Cluster that uses Disk Data storage
can be greatly improved by separating the data node file system
from any tablespace files (undo log files and data files), and
placing these on different disks. In early versions of NDB
Cluster, there was no direct support for this in NDB Cluster,
and it was necessary to achieve this separation using symbolic
links. NDB Cluster now supports the data node configuration
parameters
FileSystemPathDD,
FileSystemPathDataFiles,
and
FileSystemPathUndoFiles,
which make the use of symbolic links for this purpose
unnecessary. For more information about these parameters, see
Disk Data file system parameters.